Cylinder head and method of reconstructing same

ABSTRACT

A cylinder head has a cast iron body member, one end of which is recessed to accommodate a circular disk-like insert of an iron, chromium, nickel alloy. The insert forms one wall of the water jacket portion of the cylinder head, and its external surface provides the combustion surface of the cylinder head. The periphery of the insert is spaced inwardly of the bolt holes and water ports of the cylinder head. The insert also has boss portions which form the lower part of the valve port bosses and the injector boss. The insert is brazed to the body member at its periphery and at the abutting boss portions. The flange at the opposite end of the cylinder head is cast steel. When fabricated as a new part, the body member may be of cast steel and integral with the flange.

United States Patent [1 1 Jones, Jr. et al.

[ 1 Aug. 20, 1974 CYLINDER HEAD AND METHOD OF RECONSTRUCTING SAME [76] Inventors: Robert H. Jones, Jr.; Richard B.

Jones, both of RR. No. l Box 267, Hibbing, Minn. 55746 [22] Filed: Mar. 5, 1973 [21] Appl. No.: 338,068

[52] US. Cl 123/4l.82 A, 29/1564, 29/401, 123/193 H [51] Int. Cl F02f 1/30 [58] Fieldof Search 123/41.82 A, 193 C, 193 CH, 123/193 H [56] References Cited UNITED STATES PATENTS 1,941,947 1/1934 MacPherson l23/4l.82 A 3,289,649 12/1966 Lamm 123/193 C 3,449,815 7/1969 Jones et a1...... 123/193 H 3,593,406 7/1971 Jones et al...... 123/193 C 3,620,137 11/1971 Prasse 123/193 C 3,657,078 4/1972 Schweikher 123/193 C I a, :1" I4 Primary ExaminerManuel A. Antonakas Assistant Examiner-Daniel J. OConnor Attorney, Agent, or Firm--Bayard Jones [5 7] ABSTRACT A cylinder head has a cast iron body member, one end of which is recessed to accommodate a circular disklike insert of an iron, chromium, nickel alloy. The insert forms one wall of the water jacket portion of the cylinder head, and its external surface provides the combustion surface of the cylinder head. The periphery of the insert is spaced inwardly of the bolt holes and water ports of the cylinder head. The insert also has boss portions which form the lower part of the valve port bosses and the injector boss. The insert is brazed to the body member at its periphery and at the abutting boss portions. The flange atthe opposite endof the cylinder head is cast steel. When fabricated as a new part, the body member may be of cast steel and integral with the flange.

14 Claims, 9 Drawing Figures PATEN TED M182 01974 SHEU 1 0f 3 Y This invention relates to an improved cylinder head for the cylinders of a large internal combustion engine and to a method of making same by the reconstruction of a used cylinder head. The invention is illustrated with respect to a cylinder head for use in large diesel engines, such as used in locomotives, although it is understood that the invention is applicable to other types of engines. The present invention is an improvement over that described in our prior US. Pat. No. 3,593,406, granted July 20, 1971, which relates to a method of reconstructing worn cylinder heads.

One of the defects, other than corrosion, in the worn cylinder heads described in that patent which is remedied by the process described therein is the development of one or more cracks in the combustion surface of the original cylinder head. These cracks extend between a valve seat and the injector opening. The method of reconstruction disclosed in that patent contemplated the replacement of the entire lower portion of the cylinder head with a new portion in the form of an iron casting, the original cylinder head also being of cast iron. The new portion was provided with passages for the valves and the injector and was cored to provide a water jacket overlying the combustion surface, the new portion being affixed to the old portion by brazing. Such reconstructed cylinder head could be expected to have a life comparable to the life of the original cylinder head, but it nevertheless was subject to the same type of wear, including the development of cracks, as the original.

According to our present invention, the reconstructed cylinder head provides a heat and corrosion resistant combustion surface formed of an iron and chromium containing alloy, and it is in the form of an insert extending for substantially the full area of the combustion surface, as contrasted with the replacement of the entire lower portion of the cylinder head. The iron-chromium alloy insert has an expected life of several times the life of a cylinder head having a cast iron combustion surface.

The alloy insert for a cast iron cylinder head may be any castable iron-chromium alloy having a coefficient of expansion substantially the same as cast iron. Preferably, the alloy contains both nickel and chromium with iron and carbon.

An insert that has given particularly satisfactory results for heat resistance and stability against cracking has the following analysis:

The following Table I gives the compositions of four other alloys which are suitable for these inserts.

TABLE 1 Insert C Cr Ni Si Mn Mo Fe A 0.22 21.5 1 1.5 0.8 1.35 0 balance B 0.40 21.16 3.0 0.19 9.16 0 balance C 1.0 4.0 0 2.5 0.6 8.5 balance D 2.02 12.3 42.1 1.63 1.13 6.7 balance The above alloys not only have satisfactory heat resistance and temperature stability but also may be brazed to cast iron using a silver brazing alloy such as that disclosed in our US. Pat. No. 3,593,406, at a temperature of approximately 1,325 F. for a time interval of, for example, approximately 2 hours, as disclosed in said patent, the disclosure of which patent is hereby incorporated by reference insofar as consistent with the instant disclosure.

In general, suitable alloys are chromium or chromium-nickel iron alloys having a carbon content of 0.2 2.1 percent, a chromium content of 4 22 percent, a nickel content of 0 percent and preferably a nickel content of 40 60 percent, with the balance predominantly iron.

Minor amounts of other elements, such as silicon, tungsten, vanadium and manganese, which are generally present in stainless steels, for example, may also be present and give some advantage of ductility and heat resistance but are not necessary, and elements such as sulfur and phosphorus are kept at a minimum.

A feature of the present invention is that the insert comprises only the lower wall of the water jacket overlying the combustion surface. This not only results in considerable cost saving in material, but it also permits the provision of additional heat-radiating fins extending into the cooling medium and located at points which are opposite to the area most subject to cracking.

Another advantage of the present invention is that the iron-chromium alloy insert does not have the oxidation scale on its surface which is characteristic of cast iron and which cannotreadily be removed from the water jacket cavity of a cylinder head casting of cast iron. Thus, the water cavity surface of the insert will transfer heat from the combustion surface to the water much more efficiently than if the part were made of cast iron for the reason that the oxidation scale on cast iron reduces the heat transfer characteristics very markedly.

In certain types of diesel engine construction, the cylinder heads are maintained in side-by-side position and urged against the liner by hold-down clamps. It has been found that the upper portion of the cylinder head, referred to as the flange, which is engaged by the hold-down clamps, is also subject to cracking, especially through the bolt holes. The present invention contemplates a cylinder head in which the flange is a separate element fabricated from cast steel, which has much greater tensile strength and ductility than a cast iron flange. Thus, the probability of the flange cracking or breaking due to fatigue is greatly reduced.

Other objects, features and advantages of our invention will become apparent as the description proceeds.

1n the drawings: FIG. 1 is an elevation of a preferred embodiment of our invention, also showing its relationship to the liner;

FIG. 2 is a horizontal section taken along line 22 of FIG. 1;

FIG. 3 is a horizontal section taken along line 3-3 of FIG. 1;

FIG. 4 is a section taken along lines 44 of FIGS. 2 and 3, with certain parts removed for purpose of clary;

FIG. 5 is a plan view of the insert;

FIG. 6 is a bottom view of the cylinder head in its entirety;

FIG. 7 is an exploded elevation of the cylinder head; and showing a portion of the liner in phantom;

FIG. 8 is an enlarged fragmentary vertical section of a portion of FIG. 7; and

FIG. 9 is a bottom view of a different type of cylinder head embodying our invention.

In FIG. 1, the reference numeral 10 designates the cylinder head as a whole which overlies the liner 11. The cylinder head and the liner cooperate to form a combustion chamber 12, and the liner 11 provides a water cavity 13. It will be noted that the lower periphery of the cylinder head is stepped at 14 to provide a proper seal with the liner.

As shown in FIGS. 2 and 3, the cylinder head provides a plurality of bolt holes 15 so that it may be bolted to the liner. The upper portion of the cylinder head comprises the flange 16. Hold-down clamps 17 and bolts 18 engage the flange and hold the cylinder head and liner assembly in position in the engine structure, referred to as the A frame or block.

The undersurface of the cylinder head, referred to herein as the combustion surface 20, constitutes the upper surface of the combustion chamber 12.

The lower portion of the cylinder head can be referred to as the water jacket portion 21 which provides various cavities C (FIG. 4 only) for the circulation of a suitable cooling medium. Extending through the water jacket are various cylindrical elements or bosses 22a and 23a providing valve ports 22 and an injector passage 23 respectively which open out into the combustion surface 20. The valve ports terminate in valve seats 24, shown in FIGS. 4 and 6. In addition to the elements 22a and 230, as well as the bosses 15a surrounding the bolt holes 15, there are certain ribs 25 and 26 which serve as water deflectors and also as reinforcing ribs for the combustion surface 20. Also, as shown in FIG. 3, there is a boss 27 which accommodates a normally plugged compression test passageway, not shown. Water ports 31 communicate with liner cavity 13.

In illustrating the relationship of the elements 22a and 23a to the water cavities C, the boss 27 and the ribs 25 and 26 have been omitted in FIG. 4 for the purpose of clarity. It will be seen from FIG. 4 that the valve ports 22, which contain exhaust valves, not shown, communicate with an exhaust outlet 28 located right above the water jacket portion 21. The valve ports 22 terminate at the lower surface of the exhaust outlet 28, although provision is made in the upper part of the cylinder head to receive the valve stems.

The injector boss 23a, however, extends upwardly through the exhaust outlet 28 and through a water cavity (not shown) located above the upper wall of the exhaust outlet.

According to our invention, when a worn cylinder head is received, the combustion surface thereof is cut out by means of a plunging cutter to provide a recess 34 which extends up into the water jacket portion 21, as shown in FIG. 7. Also, the original integral flange 16 is removed by a suitable lathe turning operation so that all that remains of the original cylinder head is a central body member 35 in the form of a cast iron cylinder having the various openings and cavities as indicated in FIGS. 1 and 4.

Then the alloy insert 36, as shown in FIGS. 5 and 7, is inserted into the recess 34 and brazed, as described in our aforesaid prior patent, to provide the lower half of the water jacket portion 21 of the reconstructed cylinder. As indicated in FIG. 5, the alloy insert provides the lower portions of the various ribs 25, 26, the boss 27, and the bosses 22a and 23a which surround the ports and passageway 22 and 23.

Prior to assembly and brazing, the insert 36 and the cut surfaces of the body portion 35 are prepared for the brazing operation as described in our aforesaid patent.

The advantage of the present arrangement is that it is not necessary to drill out the water ports 31 and the bolt holes 15 in the insert, nor to align the bolt holes as in the case where the entire water jacket portion is re placed as in our prior patent. However, the bosses 22a and 23a of the insert 36 must be aligned and drilled prior to brazing. As previously indicated, the insert is in the form of a special alloy casting of which the mating surfaces are machined, as well as the combustion surface 20.

Preferably, the recess 34 is a stepped recess, as shown in FIG. 7, providing at certain points only, (e-.g., at boss 27 and ribs 25, 26) a downwardly facing shoulder 39. The insert 36 then is formed with a flange 37, the upper surface 38 of which mates with the downwardly facing surface of the shoulder 39. The surfaces which are brazed to each other are the cylindrical surfaces 40 and 41, also 40a and 41a where present. A clearance of substantially 0.005 inches between the surfaces 40, 41 is provided to accommodate the wafer of brazing alloy which in this case is in the form of a strip wound 42 about the cylindrical surface 40 of the insert 36, as shown in FIG. 8. Fragmentary wafers 43 are placed between horizontal mating surfaces 38 and 39 at points 38, shown in FIG. 5. Die cut wafers 45 are also placed between the horizontal mating surfaces of boss 27 and of ribs 25, 26, and similar wafers (not shown) between the horizontal mating surfaces of bosses 22a and 23a.

The strip 42 may become partially displaced between the surfaces 40 and 41 when the insert is initially fitted into the recess 34. However, due to capillary action (sweating), the brazing alloy tends to distribute itself more or less uniformly over the cylindrical surfaces 40 and 41. Also at places above the points 38 (FIG. 5) the material of wafers 43 and 45 will sweat over the cylindrical surfaces 40a and 41a.

As a result of this stepped arrangement, as shown in FIG. 4, flange 37, as well as the lower wall of the water jacket 21, is at a different level than the mating surfaces of the bosses 22a and 23a. In the embodiment shown, the flange 37 is inch thick, and the mating line of the bosses extends above the upper surface of the flange by a distance of 7% inch. This provides a stronger boss construction so that the insert 36 is better adapted to resist the combustion forces. The plunging cutter above mentioned is well adapted to cut out the recess 34 in a stepped form.

The insert 36 is preferably of a diameter such that its peripheral edge overlaps the liner 11, as shown in FIG.

The portions of a cast iron combustion surface most subject to cracking are indicated by the letter A in FIG. 6. Our invention provides heat dissipating fins 44 opposite to the areas A, the use of an insert permitting the formation of the fins, which otherwise would be difficult to core in the prior art arrangement.

In the reconstruction of a used cylinder head, a flange 16 is machined out from a cast steel having substantially the same coefficient of expansion as cast iron. We have found that a 1,025 steel casting has a coefficient of expansion very close to that of class 40 iron, which is the iron customarily used in casting cylinder heads. Also, it has a tensile strength nearly twice as great as a class 40 iron, and a low carbon content gives it a considerable amount of ductility. Thus, it is possible inreconstructing the cylinder head to provide a reconstructed cylinder head of which the flange 16 is substantially free from the possibility of cracking or breaking due to fatigue; at least the probability is greatly reduced.

This 1,025 steel has a critical temperature about 200 F .-higher than class 40 iron with the result that the possibility of modification of its tensile strength and ductility properties during the furnace brazing operation is rather remote. As a result, the steel flange is not likely to develop cracks between the bolt holes and the casting surface under service conditions. The cast steel flange 16 is brazed to the body member 35 insubstantially the same manner as described with respect to the insert 36; that is, a die cut wafer of the brazing alloy, preferably the silver brazing alloy described in our aforesaid earlier patent, is placed between the horizontal mating surfaces, and additionally a strip of such alloy may be wound around the cylindrical surfaces to be brazed.

After the parts have been assembled with the brazing alloy, the assembly is moved through an oven, as described in our aforesaid previous patent, for the time interval and at the temperature described therein, namely, approximately 2 hours, at a temperature sufficient to raise the casting to approximately 1,325 F.

Where our cylinder head is to be fabricated as a new part, the same process of manufacture as described herein with respect to a reconstructed cylinder head may be followed, except that the body portion 35 is a new casting. However, it is preferred that the body portion 35 and the flange 16 be cast integrally from 1,025 cast steel since the cost of fabrication will be somewhat reduced, and since the metallurgical properties of the cast steel body portion 35 are satisfactory for long life cylinder head service. As previously indicated, the coefficient of expansion of the 1,025 steel casting is substantially the same as that of the iron-chromium alloy of the insert 36.

It will be noted that the upper surface of the cylinder head 10 is recessed with the result that the flange element 16, when fabricated separately as shown in FIG.

' 7, is in the form of a stepped ring having bolt holes 15,

aligned with the bolt holes 15 of the body portion 35.

It will be understood that the term bolt holes is used generically herein to indicate an opening for receiving securing means which may be of any one of several types, such as bolts, studs or dowels.

Our invention is-also applicable to engines in which a single cylinder head casting 46 is provided for several cylinders. As shown in FIG. 9, a separate insert 36' is provided for each cylinder.

The casting 46 is provided with the usual bolt holes 15' which correspond to the holes 15 of FIG. 6 and the usual water ports 31 which correspond to the water ports 31 of FIG. 6, both of which surround the insert 36 as shown in FIG. 9. For purpose of clarity, the bolt holes 15 and water ports 31 are shown only with respect to one insert 36 but it will be understood that they surround each of the four inserts 36' shown.

In some cases a lesser number of valve ports are used, depending on engine design. Also, in the case of electrical ignition, a spark plug can be substituted for the injector in the passageway 23.

Although only preferred embodiments of our invention have been shown and described herein, it will be understood that various modifications and changes can be made in the constructions shown without departing from the spirit of our invention, as pointed out in the appended claims.

We claim:

1. A cylinder head for a large internal combustion engine comprising a body member adapted to provide a combustion surface at one end, a water jacket portion adjacent said combustion surface, said water jacket portion having both upper and lower walls, a plurality of apertured bosses extending through said water jacket portion and providing ports opening into said combustion surface, bolt holes located around the periphery of said body member, said lower wall of said water, jacket portion comprising an insert of an iron alloy containing chromium and having substantially the same coefficient of expansion as the material of said body member, the peripheral edges of said insert being spaced inwardly from said bolt holes, said body member being recessed to accommodate said alloy insert, and the lower surface of said insert providing a combustion surface for said cylinder head of said ironchromium alloy material, said insert being brazed to the adjacent surface portions of said recessed body member, said alloy insert providing the lower portions of said port bosses and being brazed to the upper portions thereof.

2. A cylinder head as claimed in claim I in which the insert is an alloy having a chromium content of 4-22 percent by weight, a nickel content of 0-60 percent by weight, a carbon content of 0.2-2.1 percent by weight, and the balance predominantly iron.

3. A cylinder head for a large internal combustion enportion having both upper and lower walls, an injector boss and a plurality of valve port bosses extending through said water jacket portion and providing ports opening into said combustion surface, bolt holes located around the periphery of said body member, water ports located around the periphery of said body member for communication with the water cavity of a cylinder liner, said lower wall of said water jacket portion comprising an insert of an iron alloy containing chromium having substantially the same coefficient of expansion as the material of said body member, the peripheral edges of said insert being spaced inwardly from said bolt holes and water ports, said body member being recessed to accommodate said alloy insert, and the lower surface of said insert providing a combustion surface for said cylinder head of an iron-chromium alloy material, the peripheral portion of said insert being brazed to the adjacent surface portions of said recessed body member, said alloy insert providing the lower portions of said injector and valve port bosses and being brazed to the upper portions thereof.

4. A cylinder head as claimed in claim 3 in which the insert is an alloy having a chromium content of 4-22 percent by weight, a nickel content of -60 percent by weight, a carbon content of 0.2-2.1 percent by weight, and the balance predominantly iron.

5. A cylinder head as claimed in claim 4 in which the nickel content is 40-60 percent.

6. A cylinder head as claimed in claim 3 in which the insert is an alloy having a composition by weight of:

C l.2-2. l Cr l0.0l2.5 Ni 40.0-60.0 Mo 0.0-7.0 Si 1.0-3.0 Mn 1.0-2.0 Fe 20.0-35.0 W 0.0-l.0 V 0.0-l.0 S 0.00.l P 0.0-0.l

7. A cylinder head as claimed in claim 3 in which the alloy hasthe approximate composition by weight:

C Cr Ni Mo Si Mn W 8. A cylinder head as claimed in claim 3 which includes a plurality of fins extending upwardly from the upper surface of said insert at points between said valve port bosses and said injector boss.

9. A cylinder head as claimed in claim 3 in which said body member has a laterally extending flange at its upper end for engagement by hold-down means.

10. A cylinder head as claimed in claim 9 in which said flange is separately formed from said body memher, said body member being of cast iron, and said flange being of cast steel and having a portion abutting the upper surface of said cast iron body member-and being brazed thereto.

11. A cylinder head as claimed in claim 10 in which said flange is a ring having an internal step providing said abutting portion.

12. A cylinder head as claimed in claim 9 in which said body member and said flange comprise an integral steel casting.

13. A cylindrical head as claimed in claim 3 in which the recess of said recessed body member is a stepped recess, said insert peripheral portion fitting within the step of said stepped recess, said lower portions of said injector and valve port bosses extending upwardly beyond the level of the upper surface of said peripheral portion.

14. A cylinder head for a large internal combustion engine comprising a body member adapted to provide a plurality of combustion surfaces at one surface thereof, a water jacket portion adjacent said combustion surfaces, said water jacket portion having both upper and lower walls, a plurality of apertured bosses extending through said water jacket portion and providing ports opening into each of said combustion surfaces, bolt holes located around the periphery of each of said combustion surfaces, said lower wall of said water jacket portion comprising a plurality of inserts of an iron alloy containing chromium having substantially the same coefficient of expansion as the material of said body member, the peripheral edges of each of said inserts being spaced inwardly from said bolt holes, said body member having recesses to accommodate each of said alloy inserts, and the lower surface of each insert providing a combustion surface for said cylinder head of said iron-chromium alloy material, the peripheral portion of each insert being brazed to the adjacent surface portion of said recessed body member, said alloy inserts providing the lower portions of said port bosses and being brazed to the upper portions thereof. 

1. A cylinder head for a large internal combustion engine comprising a body member adapted to provide a combustion surface at one end, a water jacket portion adjacent said combustion surface, said water jacket portion having both upper and lower walls, a plurality of apertured bosses extending through said water jacket portion and providing ports opening into said combustion surface, bolt holes located around the periphery of said body member, said lower wall of said water jacket portion comprising an insert of an iron alloy containing chromium and having substantially the same coefficient of expansioN as the material of said body member, the peripheral edges of said insert being spaced inwardly from said bolt holes, said body member being recessed to accommodate said alloy insert, and the lower surface of said insert providing a combustion surface for said cylinder head of said iron-chromium alloy material, said insert being brazed to the adjacent surface portions of said recessed body member, said alloy insert providing the lower portions of said port bosses and being brazed to the upper portions thereof.
 2. A cylinder head as claimed in claim 1 in which the insert is an alloy having a chromium content of 4-22 percent by weight, a nickel content of 0-60 percent by weight, a carbon content of 0.2-2.1 percent by weight, and the balance predominantly iron.
 3. A cylinder head for a large internal combustion engine comprising a body member adapted to provide a combustion surface at one end, a water jacket portion adjacent said combustion surface, said water jacket portion having both upper and lower walls, an injector boss and a plurality of valve port bosses extending through said water jacket portion and providing ports opening into said combustion surface, bolt holes located around the periphery of said body member, water ports located around the periphery of said body member for communication with the water cavity of a cylinder liner, said lower wall of said water jacket portion comprising an insert of an iron alloy containing chromium having substantially the same coefficient of expansion as the material of said body member, the peripheral edges of said insert being spaced inwardly from said bolt holes and water ports, said body member being recessed to accommodate said alloy insert, and the lower surface of said insert providing a combustion surface for said cylinder head of an iron-chromium alloy material, the peripheral portion of said insert being brazed to the adjacent surface portions of said recessed body member, said alloy insert providing the lower portions of said injector and valve port bosses and being brazed to the upper portions thereof.
 4. A cylinder head as claimed in claim 3 in which the insert is an alloy having a chromium content of 4-22 percent by weight, a nickel content of 0-60 percent by weight, a carbon content of 0.2-2.1 percent by weight, and the balance predominantly iron.
 5. A cylinder head as claimed in claim 4 in which the nickel content is 40-60 percent.
 6. A cylinder head as claimed in claim 3 in which the insert is an alloy having a composition by weight of:
 7. A cylinder head as claimed in claim 3 in which the alloy has the approximate composition by weight:
 8. A cylinder head as claimed in claim 3 which includes a plurality of fins extending upwardly from the upper surface of said insert at points between said valve port bosses and said injector boss.
 9. A cylinder head as claimed in claim 3 in which said body member has a laterally extending flange at its upper end for engagement by hold-down means.
 10. A cylinder head as claimed in claim 9 in which said flange is separately formed from said body member, said body member being of cast iron, and said flange being of cast steel and having a portion abutting the upper surface of said cast iron body member and being brazed thereto.
 11. A cylinder head as claimed in claim 10 in which said flange is a ring having an internal step providing said abutting portion.
 12. A cylinder head as claimed in claim 9 in which said body member and said flange comprise an integral steel casting.
 13. A cYlindrical head as claimed in claim 3 in which the recess of said recessed body member is a stepped recess, said insert peripheral portion fitting within the step of said stepped recess, said lower portions of said injector and valve port bosses extending upwardly beyond the level of the upper surface of said peripheral portion.
 14. A cylinder head for a large internal combustion engine comprising a body member adapted to provide a plurality of combustion surfaces at one surface thereof, a water jacket portion adjacent said combustion surfaces, said water jacket portion having both upper and lower walls, a plurality of apertured bosses extending through said water jacket portion and providing ports opening into each of said combustion surfaces, bolt holes located around the periphery of each of said combustion surfaces, said lower wall of said water jacket portion comprising a plurality of inserts of an iron alloy containing chromium having substantially the same coefficient of expansion as the material of said body member, the peripheral edges of each of said inserts being spaced inwardly from said bolt holes, said body member having recesses to accommodate each of said alloy inserts, and the lower surface of each insert providing a combustion surface for said cylinder head of said iron-chromium alloy material, the peripheral portion of each insert being brazed to the adjacent surface portion of said recessed body member, said alloy inserts providing the lower portions of said port bosses and being brazed to the upper portions thereof. 